Dinosaur Proteins

Scientists have detected protein sequences from a 68 million year old Tyrannosaurus rex fossil. Like wow! Until last week, I would have said it was impossible.

Let me explain why this is so cool.
1. 68 million years is such a long time, it’s hard to contemplate.
2. Proteins generally don’t last long because organic materials decay. This is a giant soup bone that has been in the back of the fridge for millions of years.
3. Fossils form when minerals replace the components of bone, so nearly all fossils are preserved bones. Sometimes paleontologists find the impressions of hair, feathers or organs, but the actual tissue is long gone.
4. Collagen, the protein they managed to extract, is usually not preserved. Think about a human skull. Where is the nose? Noses are made of collagen, so they don’t fossilize. Tweak your nose. It bends because the inner structure is made of collagen.
5. The collagen they did extract was from the center of the femur (thigh bone). Scientists speculate that this T. rex was preserved in an oxygen-free environment which prevented the decay of some soft tissue.

The peptide sequences from T. rex were compared to similar peptides from living animals. More similarities were found between T. rex and living birds (chickens and ostriches) than between T.rex and alligators. This provides further evidence that living birds are derived from theropods (bipedal, meat-eating dinosaurs).

The New York Times science article can be seen here.

The scientific paper is:
C.L. Organ, M.H. Schweitzer, W. Zheng, L.M. Freimark, L.C. Cantly and J.M Asara, Molecular Phylogenetics of Mastodon and Tyrannosaurus rex, Science, 320: 499 (2008).